At what point must they receive protections stronger than that a child gets? Many 17 year olds know what a percent is. Say the 17 year olds in an honors math

At what point must they receive protections stronger than that a child gets? Many 17 year olds know what a percent is. Say the 17 year olds in an honors math class. Yet we restrict them to the extent they cannot vote nor sign contracts (with very few exceptions that require parental signatures). So if we need to apply the same level of protections, does that not also justify taking away rights like voting (assuming taking it away from educated 17 year olds is justified)?